December 27, 2006


John Hancock Tax-Exempt Series Fund
601 Congress Street
Boston, MA 02210

RE:  John Hancock Tax-Exempt Series Fund (the "Trust")
       John Hancock Massachusetts Tax-Free Income Fund
       John Hancock New York Tax-Free Income Fund (the "Funds")
       File Nos. 33-12947; 811-5079 (0000811921)
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Ladies and Gentlemen:

In connection with the filing of Post Effective Amendment No. 27 under the
Securities Act of 1933, as amended, and Amendment No. 28 under the Investment
Company Act of 1940, as amended, for John Hancock Tax-Exempt Series Fund (the
"Trust") it is the opinion of the undersigned that the Trust's shares when sold
will be legally issued, fully paid and nonassessable.

In  connection  with this opinion it should be noted that the Trust is an entity
of the type generally known as a  "Massachusetts  business trust." The Trust has
been duly organized and is validly  existing under the laws of the  Commonwealth
of  Massachusetts.  Under  Massachusetts  law,  shareholders  of a Massachusetts
business trust may be held  personally  liable for the obligations of the Trust.
However,  the Trust's Declaration of Trust disclaims  shareholder  liability for
obligations of the Trust and indemnifies  the  shareholders of a Fund, with this
indemnification to be paid solely out of the assets of that Fund. Therefore, the
shareholder's risk is limited to circumstances in which the assets of a Fund are
insufficient to meet the obligations asserted against that Fund's assets.


                                     Sincerely,


                                     /s/Alfred P. Ouellette
                                     ----------------------
                                     Alfred P. Ouellette
                                     AVP, Senior Counsel and
                                     Assistant Secretary